1. Field of the Invention
The present invention relates generally to an optical path simulation CAD system and method for use in the structural design of a laser printer or other apparatuses having an optical system, and, more particularly, to an optical path simulation CAD system and method capable of displaying, for verification, a trace of beams of light as it is on a three-dimensional optical model.
2. Description of the Related Arts
It has hitherto been common in the automatic computer-aided design of an optical structure used for electrophotography in laser printers, etc. to two-dimensionally convert, for examination, the behaviors of beams of light in a three-dimensional structure. More specifically, a two-dimensional drawing is created in which necessary optical components such as a polygon mirror are arranged on an optical path extending from a laser light source to a photosensitive drum providing an image forming face, to thereby define the optical path, and then verification is made of behaviors of beams of light in the three-dimensional structure while viewing the two-dimensional drawing. The designing works are thus iterated to obtain an optimum structure. In this case, for further detailed examination, a trial production is often carried out in which a pseudo structure is actually produced to form the optical path and experimented in a practical situation. Items hard to grasp through the two-dimensional examination can thereby be compensated for.
In order to precisely grasp the positions of arrangement and angles of the optical components such as a mirror within a three-dimensional space, however, the structure must be determined gradually while iterating the geometric calculations, resulting in a time-consuming work. In spite of the three-dimensional arrangement of the actual apparatus, design and examination are effected in a two-dimensional fashion, so that it is difficult and time-consuming to grasp correct behaviors of beams of light. Furthermore, due to its accumulation of human judgments and calculations, errors may often occur and the resultant design modifications and repeated trial productions may need a lot of costs and time. In addition, the trial production based verification is problematic in the accuracy due to its human intervention, with the result that repetition of the trial production may often be required.
It is therefore an object of the present invention to provide an optical path simulation CAD system and method ensuring an appropriate design and verification by three-dimensionally representing on a screen the behaviors of beams of light most approximate to the real object by use of a pseudo three-dimensional optical model in lieu of trial production.
According to a first aspect of the present invention there is provided an optical path simulation CAD system comprising a model creation unit for creating a three-dimensional optical model in which one or more optical components (a polygon mirror, an xcex8 lens, a cylindrical lens, etc.) are disposed on an optical path extending from a light source to a final arrival position; and an optical axis auto-creation unit for figuring out optical axes indicative of behaviors of beams of light in the three-dimensional optical model on the basis of predetermined set parameters, to provide displays of the optical axes in the three-dimensional optical model, for verification. The optical axis auto-creation unit defines the optical axis diameter D and the color of a beam of light emitted from the light source, the optical axis auto-creation unit creating and arranging a cylindrical optical axis model having a length L starting from the light source and ending in an input surface of a next adjacent optical component lying on the optical path. The optical axis auto-creation unit can vary the optical axis diameter D of the optical axis model as a function of the distance from the starting point. For example, the optical axis diameter D may be reduced in inverse proportion to the distance. For the optical component(s) interposed between the light source and a final arrival position, the optical axis auto-creation unit creates output-side optical axis model(s) in conformity with optical functions of the optical component(s) from input optical axis model(s), to arrange the output-side optical axis model between the optical component and a next adjacent optical component or the final arrival position. The following is a case where for example a movable reflecting mirror (galvano mirror), the polygon mirror, a lens, etc., are used as the optical components. In case the optical component lying on the optical path is a movable reflecting mirror that is capable of swinging around a predetermined rotational axis, the optical axis auto-creation unit may be able to designate as control parameters the position of the rotational axis and the angle of a reflection surface within a three-dimensional space, the optical axis auto-creation unit automatically creating and arranging reflected optical axis models from input optical axis models on the basis of the control parameters. In case the optical component lying on the optical path is a polygon mirror that has a plurality of mirror faces formed on its periphery and that rotates at a certain angular velocity, the optical axis auto-creation unit previously may define the structures of the plurality of mirror faces, figure out the positions of the mirror faces within a three-dimensional space and the angles of the reflection surfaces from mirror rotational angles, and automatically create and arrange an optical axis model reflected on a specific mirror face from an input optical axis model. In case the optical component lying on the optical path is a lens, the optical axis auto-creation unit may previously define optical functions of the lens and automatically create an output-side optical axis model in conformity with the optical functions from an input optical axis model, to arrange the output-side optical axis model between the optical component and a next adjacent optical component or an image forming face. The optical axis auto-creation unit may provide a display of an optical axis ending point at a position where an optical axis model intersects the final arrival face, and record coordinates of the ending point into a file. The optical axis auto-creation unit may define a boundary wall model indicative of an optical axis extension limit around the three-dimensional optical model, and if the optical path has no final arrival position providing an ending point, set the position of the boundary wall model which the optical axis model intersects as an ending point of an extended optical axis model. The optical axis auto-creation unit may previously define time-sequential variations of control parameters of the optical components lying on the optical path extending from the light source to an image forming face, and allow the three-dimensional model to perform continuous actions in accordance with the time-sequential variations of the control parameters, to thereby display a desired ending point trace in the shape of, e.g., a letter or a symbol on a final arrival face and to record coordinates of the ending point into a file. In such an event, the optical axis auto-creation unit preferably converts coordinate values of the ending point coordinates recorded in the file, into dot data, for the output from a printer.
In this manner, the optical path simulation CAD system of the present invention enables the behaviors of beams of light most approximate to the real object to be three-dimensionally verified on a screen by means of a pseudo three-dimensional optical model in lieu of the trial production. In addition, all complicated calculation expressions required for the behaviors of beams of light are stored and executed on the computer, so that man-interventional portion is reduced, making it possible to eliminate various unnecessary wastes that have hitherto occurred and thus to ensure an effective design. It is therefore possible in e.g., a printer having an optical system such as a laser printer to correctly grasp the track of the beams of light emitted from the light source and passing through components such as the lens, mirror and prism, and to represent the trace of the beams of light as it is within the three-dimensional space, and to replace points on the optical path final arrival face by dots to thereby form images of arrival points of a plurality of optical paths, for the display in the shape of letters or symbols. Furthermore, in case of the printer or other printing apparatuses, it is also possible not only to display on a screen the results of image formation on the beam-of-light trace final arrival face but also to print the same, whereby a pseudo check can be made as if the print were experimentally effected by the real apparatus. This also allows, upon the optical system structure design, a pseudo verification of the optimum arrangement of the related components or of whether the output control parameters for letters or symbols are proper or not as the printing apparatus, thereby achieving a considerable saving of the costs and time.
According to a second aspect of the present invention there is provided an optical path simulation method comprising the steps of creating a three-dimensional optical model in which one or more optical components are disposed on an optical path extending from a light source to a final arrival position; and calculating optical axes indicative of behaviors of beams of light in the three-dimensional optical model on the basis of predetermined set parameters, to provide displays of the optical axes in the three-dimensional optical model, for verification. The details of the optical path simulation method are the same as those of the apparatus configuration.
The above and other objects, aspects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.